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The link between premature menopause and a woman’s reproductive history

A study which looked at the reproductive history of more than 51,000 women has found a link between premature or early menopause and an early first menstruation. The number of children birthed during their reproductive history also influenced the age of menopause. For instance, women who got their first period before age 12 and had no children were five times more likely to experience premature menopause than women who had their first period at age 12 or later, and had two or more children.

Menopause is the time in most women’s lives when menstrual periods stop permanently, and they are no longer able to bear children. When menopause occurs before the age of 40, it is referred to as premature menopause. If menopause occurs between age 40 and 44, it’s considered early menopause.

As to why menopause exists in the first place, the jury isn’t out yet but we have some interesting hints. A study on killer whales suggests menopause emerged as a genetic safeguard to the legacy of the family, reducing competition for younger females.

Premature menopause can be caused by a variety of factors, the most common cause being premature ovarian failure. Other causes include damage to the ovaries by chemotherapy and/or radiation treatments, or surgical removal of the ovaries.

Researchers from the University of Queensland, Australia, wanted to know if a woman’s reproductive history could also influence premature menopause. With this aim, they combed through nine observational studies which totaled 51,450 participants from Australia, Japan, U.K., and Scandinavia. The data was adjusted for various factors that might influence menopause age like marital status, smoking, body mass index (BMI) or year of birth.

The year of birth is particularly important to normalize among the participants. Two-thirds of the women involved in the study were born between 1930 and 1949, a time when contraceptives were far less common and when women had their first period significantly later than today.

The median age of menopause was 50 which is totally expected. Among all the participants, 2 percent experienced premature menopause and 7.6 percent experienced early menopause. However, once they dived into the data more granularly, some interesting patterns emerged. The incidence of premature and early menopause was 5.2 percent and 9.9 percent, respectively, among women who had their first period before age 12 and birthed no children, as reported in the journal Human Reproduction.

Having your first period before 12 does not necessarily put you at risk of premature menopause as the current findings imply a correlation, not causation. Furthermore, the study has its limitations. The age of first menstruation, for instance, was self-reported and there’s always the risk that some women might have incorrectly recalled the age.

Nevertheless, doctors may decide to prepare women with no children and an early first menstruation for the possibility of early menopause. This might help them make more informed decisions. For instance, a woman who is aged 35 and is at risk of experiencing menopause at age 40 might want to ‘hurry up’ if she wants to have children.

“[the study] provides an opportunity for clinicians to include women’s reproductive history alongside other lifestyle factors, such as smoking, when assessing the risk of early menopause, and enables them to focus health messages more effectively both earlier in life and for women at most risk. In addition, they could consider early strategies for preventing and detecting chronic conditions that are linked to earlier menopause, such as heart disease,” said Professor Gita Mishra, Professor of Life Course Epidemiology and Director of the Australian Longitudinal Study on Women’s Health at the University of Queensland, Australia.

“The message for everyone to take on board from this and other similar studies is to think of the timing of menopause as a biological marker of reproductive ageing, which has implications for health and the risk of chronic diseases. So if we want to improve health outcomes in the later life, we need to be thinking about the risk factors through the whole of a woman’s life from the early years and the time of their first period through to their childbearing years and menopause,” Mishra said.